Field of the Invention
The present invention relates to generally linear vibrational motors. In particular a low Z profile linear vibrational motor is described.
Related Art
Vibrator motors are used as a sensory feedback device. Vibrators are classified into different types such as iron-core, brushless, flat or pancake and linear vibrators etc. Conventional linear vibrators are configured in such a way that the mechanical vibration produced is due to the displacement of a vibratory mass when directly acted upon by an actuator. Unfortunately, however, due to the direct interaction between the actuator and the vibratory mass, the displacement of the vibratory mass (and therefore the magnitude of the vibration generated) is limited to no more than the displacement provided by the actuator itself. Accordingly, in order to increase the vibration generated by the conventional linear vibrator, the actuator must by necessity provide a greater displacement to the vibratory mass resulting in a larger actuator that may be both inefficient, power-hungry and not well suited for used in small portable devices.
In order to make a thinner (i.e., small Z) linear vibration motor, the dimensions in X and Y of the vibratory body would have to be relatively large predisposing the large, thin vibratory body to vibrational modes in X and Y. These attempts to further reduce the height by flattening the vibratory mass have resulted in instability in both the X and Y directions, commonly causing motor failure. This problem has resulted in a design limit for conventional linear vibrators of roughly 3 mm in height. Another popular design for use in applications requiring a thin configuration is a coin motor (also known as a pancake motor). The coin motor relies on a spinning disc to create vibrations. Unfortunately the necessity of maintaining a circular shape means that any increase in the mass of the disc, without making the device thicker, must be accomplished through an expansion of size in both X and Y directions resulting in a larger overall footprint.
Accordingly, a scalable and efficient vibratory motor suitable for use in small devices is desired.